Safari Books Online is a digital library providing on-demand subscription access to thousands of learning resources.
Visual design techniques like beveling and shadows can make elements appear tappable. Pictory and GroupMe both use these effects to make it readily apparent which controls can be tapped.
It is important to apply this effect properly though. Yelp’s search button doesn’t look like a button, whereas every element in this form looks like a button, even the field labels.
Use common visual design techniques to indicate tappable controls. But apply 3D effects judiciously; extra shadows and bevels can decrease readability.